Exposure to family members w/ Major Depression ups risk

The risk of major depression in both men and women increases with the number of family members with major depression...

...as well as with exposure to major depression during formative years (1-18). Researchers published their findings online ahead of print in JAMA Psychiatry.

“Major depression aggregates within families,” wrote researchers from Copenhagen, Denmark, “but how family history of major depression confers risk of major depression over the life course is unclear. Such knowledge is important to identify and prevent possible depressogenic effects of family environment.” 

The cohort study included 2.9 million individuals born in Denmark between 1960 and 2003 who were followed for major depression starting at age 15. Among them, 37,970 men (2.6%) and 70,223 women (5%) developed major depression.

Exposure to either a mother, father, or sibling with major depression was associated with a 2-fold higher risk of major depressive disorder in men. Additionally, the risk grew with the number of family members with major depression, according to the study. In women, the pattern was similar, researchers added.

The age of family members at their depression onset was associated with major depression risk in women but not in men, the study found. In women, for instance, the risk of depression increased with the onset of major depression in mothers before age 69. Compared with maternal depression onset at age 70 or older, incidence rate ratios for major depression in women were 1.64 with maternal depression onset before age 40, 1.62 with maternal depression onset between ages 40 and 49, 1.56 with maternal depression onset between ages 50 and 59, and 1.67 with maternal depression onset between ages 60 and 69. 

In men, and similarly, in women, exposure to major depression in family members while younger than age 30 was associated with an increased risk of depression. For example, incidence rate ratios for major depression in men were 1.95 with exposure to maternal major depression at age 12 months or younger, 2.31 with exposure between ages 1 and 11 years, 2.18 with exposure between ages 12 to 18 years, and 1.42 with exposure between ages 19 and 29 years.

“Individuals exposed when 30 years or older,” researchers wrote, “had [a] markedly lower risk.”
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